Continuity mistake: When Homer is smelling the BBQ the smoke that's in front of him vanishes instantly. (00:03:30)
Continuity mistake: When Homer is hanging out of the window there is a blue curtain tie visible however this disappears in the long shot. (00:03:30)
Continuity mistake: When Ned starts talking about the Leftorium during his barbecue, Marge's dress is pink in one shot. (00:04:05)
Continuity mistake: The colour of Bart's plate at the BBQ changes between shots. It goes from dark blue to light blue. (00:07:40)
Continuity mistake: When the family is having dinner, the glasses on the table keep disappearing/reappearing between shots. (00:09:30 - 00:10:30)
Revealing mistake: When Barney is drinking beer at Moe's Tavern, his chest is, for one frame, the same color as his shirt. (00:11:30)
Continuity mistake: When Homer buys Ned's living room for $75, Bart is wearing a pink "Ned loves Maude" T-Shirt but by the end of the scene where Bart says "Hands off my china hutch." his shirt is the standard orange shirt. (00:14:40)
Character mistake: When Homer discovers that the Leftorium is going out of business, there is a sign that says 'Coming Soon: Gum for Less' beside the store. Later on, though, Ned says the new store is becoming 'Libertarian Party Headquarters.' (00:15:50 - 00:19:15)
Suggested correction: The sign is just an advertising poster that's on a wall. It's not in front of the leftorium.
Audio problem: When Ned calls Homer and says "over here" his mouth doesn't move. (00:17:30)
Factual error: When Rod and Todd Flanders are roasting marshmallows in the car, Todd's marshmallow was the only one above the lighter, even though both of them have turned black. (00:17:40)
Continuity mistake: When Homer and Ned are talking after Homer tries to return the BBQ, the BBQ moves place on the lawn. Note the stepping stones. (00:17:40)
Continuity mistake: When Ned and Homer walk away from Ned's car, they are by the flower beds. Camera cuts and they are back by the car. (00:18:00)
Continuity mistake: When Mr. Burns is notified about the Leftorium, the can and can opener have disappeared from Smithers' hands. (00:19:45)
Continuity mistake: When we see Maude ringing items up on the cash register, it has no external display. When Ned is ringing items up there is an external display. (00:20:45)
Continuity mistake: At the end Todd's shirt changes from white to red. (00:21:15)
Continuity mistake: At the end, you can briefly see Dr. Marvin Monroe. The cigar he is holding instantly changes from white to brown. (00:21:25)
Continuity mistake: In the beginning, Bart's bedroom's window faces the backyard. When the bus leaves, it faces Evergreen Terrace. At the beginning of Bart's nightmare, it faces the backyard again. (00:00:55 - 00:15:45)
Other mistake: When Bart sees that Santa's Little Helper ate his homework, and the camera moves really fast, you can see that the Krusty Doll and picture frame have vanished from the desk beside his bed. (00:00:55 - 00:01:50)
Continuity mistake: When Bart realizes he forgot his permission slip, the camera shows us that the paper is half-under his pillow. However, when he got out of his bed at the very beginning, the paper wasn't under his pillow. (00:01:00 - 00:03:05)
Continuity mistake: When Bart finds out that Homer took the police badge out of the cereal box, it changes from brown to pink. The food inside the box also changes to pink. (00:01:10)